Field of the Invention
The inventions disclosed and taught herein relate generally to hydrocarbon drilling and exploration operations, and more specifically are related to fluid pressure transmission pills and their manufacture and use in support of drilling and exploration operations.
Description of the Related Art
Various types of well bore fluids are used in operations related to the development, completion, and production of natural hydrocarbon reservoirs. Typical operations include fracturing subterranean formations, modifying the permeability of subterranean formations, logging operations, and sand control, among others. Of particular interest with regard to the present inventions are fluids appropriate for use in performing managed pressure drilling (MPD) operations, particularly those in high-temperature, high-pressure hydrocarbon fields, where standard drilling fluids have an insufficient density for tripping drill pipe, wireline logging, or other operations.
Managed pressure drilling (MPD) is a relatively recent adaptive drilling process, similar in some aspects to under-balanced drilling, used to precisely control the annular pressure profile throughout the well during the course of a drilling operation, thereby reducing drilling problems. The primary objective of the MPD concept is to maintain a balanced well bore pressure within the critical tolerances defined by the pore pressure, well bore stability, and fracture pressure. For example, MPD could be used to manage and maintain the pressure between the pore pressure and the fracture pressure of a reservoir, while simultaneously compensating for the influx of fluids that may occur during drilling without encouraging such an influx. MPD uses a number of tools to mitigate the risks and costs associated with drilling wells by managing the annular pressure profile. Typical techniques applied to date have included controlled backpressure, fluid density, fluid rheology, annular fluid level, circulating friction, and hole geometry [see, Hannigan, D., SPE paper 92600, 2005].
As illustrated in numerous studies, problems in deep wells can be caused by well bore pressure deviating outside the pressure gradient window during drilling operations, resulting in non-productive time. For example, at shallow depths, if the well bore pressure deviates below the pore pressure gradient, water or gas can flow into the well bore, and a kick can occur, or in some instances the well bore may become unstable and collapse on the drill pipe. A major problem when pressure exceeds the fracture pressure-gradient is lost circulation, with a loss of mud into the formation with subsequent reservoir damage. These pressure deviation issues account for numerous drilling problems, which in turn have a significant impact on drilling costs and well performance. Consequently, new methods and systems for managing well bore pressure in drilling operations, based on managed pressure drilling (MPD) technologies, is needed to alleviate these drilling issues.
The inventions disclosed and taught herein are directed to viscous isolation pills, also referred to herein as fluid pressure transmission pills (FPTP) used during managed pressure drilling (MPD) operations. FPTP serve as a barrier to prevent intermixing of the lower density drilling fluid being utilized in the drilling operation and a heavier density fluid which is applied to achieve a total hydrostatic pressure overbalance in the fluid column that is sufficient for well control when tripping drill pipe, conducting wireline logging, or performing other subterranean operations.